Emachines upgrade?

I have an Emachines 740 with 1.6Gb Pentium 4 processor & 256Mb pc133 sdram and would like to upgrade both the processor & memory (more so the memory). Having knocked around a few websites I still can`t get a definate answer as to the maximum I can upgrade to.

Thanks to anyone that can help.

http://www.emachineupgraders.info/